Within a year, a pair of souped-up $2.7 billion blimps (price includes R&D) will be floated 10,000 feet above the District of Columbia and act as a 340-mile-wide eye in the sky, detecting incoming missiles and the like.

The design and testing phase for JLENSâ€”the Joint Land Attack Cruise Missile Defense Elevated Netted Sensor System, produced by Raytheon, a major weapons manufactuerâ€”is over, relays Program Director Doug Burgess to Popular Mechanics. Now, it is time for implementation. Or, as he puts it, "[We're] getting away from the Ph.D. engineer types running the system to the 20- or 25-year-old soldier running the system."

The idea to employ blimps to protect a city is actually not new. During World War II, London deployed a similar system to protect against Nazi air strikes. The barrage balloons, as they were called, acted as fence posts for a spool of wire that would make it difficult for planes to maneuver in the city. Basically, they were barbed wire fences suspended a few thousand feet in the air. They were also filled with hydrogen, which upon impact with a plane would explode. This is what they looked like: